Using 2-Bay not 4-Bay? PR4100

I have WD My Cloud Pro Series 16TB PR4100 4-Bay (4 x 4TB), it is becoming full,
Recently I bought 2 new drives (2 x 16TB)=32TB ,

My question is :

It’s possible if I replace all disks (4 x 4TB) with (2 x 16TB) . "using 2-Bay not 4-Bay?? without losing my data?
and what is the procedure if it possible ?